Comparison of robust H<Subscript>∞</Subscript> filter and Kalman filter for initial alignment of inertial navigation system

There are many filtering methods that can be used for the initial alignment of an integrated inertial navigation system. This paper discussed the use of GPS, but focused on two kinds of filters for the initial alignment of an integrated strapdown inertial navigation system （SINS）. One method is based on the Kalman filter （KF）, and the other is based on the robust filter. Simulation results showed that the filter provides a quick transient response and a little more accurate estimate than KF, given substantial process noise or unknown noise statistics. So the robust filter is an effective and useful method for initial alignment of SINS. This research should make the use of SINS more popular, and is also a step for further research.     

Risk management modeling and its application in maritime safety

Quantified risk assessment （QRA） needs mathematicization of risk theory. However, attention has been paid almost exclusively to applications of assessment methods, which has led to neglect of research into fundamental theories, such as the relationships among risk, safety, danger, and so on. In order to solve this problem, as a first step, fundamental theoretical relationships about risk and risk management were analyzed for this paper in the light of mathematics, and then illustrated with some charts. Second, man-machine-environment-management （MMEM） theory was introduced into risk theory to analyze some properties of risk. On the basis of this, a three-dimensional model of risk management was established that includes： a goal dimension; a management dimension; an operation dimension. This goal management operation （GMO） model was explained and then emphasis was laid on the discussion of the risk flowchart （operation dimension）, which lays the groundwork for further study of risk management and qualitative and quantitative assessment. Next, the relationship between Formal Safety Assessment （FSA） and Risk Management was researched. This revealed that the FSA method, which the international maritime organization （IMO） is actively spreading, comes from Risk Management theory. Finally, conclusion were made about how to apply this risk management method to concrete fields efficiently and conveniently, as well as areas where further research is required.     

Two-dimensional numerical simulation of water splash phenomena with and without surface tension

Two-dimensional numerical analyses were conducted and analyzed to simulate water splash produced by free falling object models starting from the resting position. The equilateral prism-shaped object models were allowed to fall onto the free surface of the water. The moving-particle semi-implicit (MPS) method was used to solve the unsteady Navier-Stokes equation for incompressible fluid flows with and without the surface tension effect. Froude numbers of 0.75, 1.0, and 1.25 were used with different model sizes for the entry velocity at the free surface. Splashes obtained by numerical computation closely agreed with the experimental results. The surface tension force, the Froude number, and the Weber number were found in these calculations to play major roles in determining various types of splash shapes. Model size was found to influence splash phenomena, even if the Froude number remained the same. The dependencies on these two nondimensional numbers and the fundamental law of similarity on water splash with and without the surface tension effect were thoroughly investigated in this research. Several two-dimensional numerical simulations are presented in this article to describe the hydrodynamic behaviors of water splash with and without the surface tension effect.     

Experimental Investigation of Impacts of Injection Timing and Pressure on Combustion and Particulate Matter Emission in a Spray-Guided GDI Engine

A detailed investigation of the impact of injection timing and injection pressure on combustion and particles of a spray-guided GDI engine was conducted, under different engine operating conditions. The results indicated that, more proportion of large particles were emitted when increasing engine load, and the peak of accumulation mode particles moved toward smaller size when rising engine speed. With retarding the injection timing, the in-cylinder pressure and heat release rate rose first and then dropped at 2000 rpm, but they continuously rose at lower or higher speed conditions. The total particles concentration curves at all cases showed a trend of U-shape, and the corresponding timing of the lowest particles concentration advanced as the engine speed or load increased. The minimum value of emitted particles first rose and then fell when increasing load at 2000 rpm conditions, and it continuously rose when increasing speed at 40 Nm conditions. Generally, injection pressure did no sensitively affect combustion process except that it showed a relatively strong impact at low load conditions. However, particulate matter could be effectively inhibited by elevating fuel pressure from 5.5 to 11.5 MPa at all cases. In detail, the total particles concentration continuously fell at low speed and mid speed-high load cases, but it showed a rose trend when further increase fuel injection pressure at mid speed-low load and high-speed conditions.     

Methods of analysis for vehicle soak time data

Vehicle soak time, the duration of time a vehicle’s engine is at rest prior to being started, and its distribution function are important transportation activity data inputs for mobile emissions inventory estimation due to their impacts on vehicle start and evaporative emissions. This paper provides vehicle emission researchers with an overview of statistical analysis methods relevant to analyzing vehicle soak time data. Many of these methods are already in use in emissions research and have appeared in the literature. These methods are reviewed and further details regarding the implementation and interpretation of these methods are provided. Statistical methods relevant to the analysis of soak time data that have yet to appear in the emissions literature, including kernel density estimation and generalized linear models, are also introduced. Advantages and disadvantages of the methods are compared and theoretical justification is provided. Issues of correlated observations and censored data are discussed. General guidelines for the analysis of soak time data, such as stratification by start type and geographical region, are established. Finally, a subset of the statistical methods discussed is used to analyze the US Environmental Protection Agency’s 3-city data.     

Slope Shift Strategy for Automatic Transmission Vehicles Based on the Road Gradient

Motivated by the development of high-precision digital maps for advanced driver assistance system (ADAS) in recent years, this study provides a new approach to solve the problems of the conventional automatic transmission vehicle travelling on sloping roads. Based on vehicle dynamics, shift problems on hilly roads are analyzed. A novel intelligent shift strategy is proposed, which consists of a dynamic shift schedule for the uphill, a safety shift schedule for the downhill, and a comprehensive economical shift schedule for the gentle slopes. A set of driver-in-loop co-simulation tests was conducted in a driving simulator that is equipped with a MATLAB/Simulink dynamics simulation platform. The test results verified the effectiveness of the new intelligent shift strategy. With the road information provided by a high-precision digital map, busy shifting can be eliminated, and improved dynamic performance can be achieved for a vehicle travelling on the uphill roads; undesired upshift can be prevented, and engine traction resistance can be used to relieve the load of braking system when a vehicle travelling on the downhill roads; also, fuel consumption can be reduced for a vehicle travelling on a gently sloped road. Consequently, this novel intelligent shift strategy offers a reliable and effective solution for improving a vehicle’s driving performance on a hilly road.     

Prediction of Hull Deflection on Damaged Warship

The appropriate prediction of the hull deflection of a severely damaged warship is an important area in the research of the warship survivability. In this paper, the asymmetrical beam bending theory is applied to set up the damaged model, a comparison of the longitudinal strength, the deflections of damaged hull subjected to both hagging and sagging moments, and shear forces is carried out. The external loads are also calculated according to different damaged positions. Finally, some results and conclusions are obtained.     

Multi-path planning algorithm based on fitness sharing and species evolution

A new algorithm is proposed for underwater vehicles multi-path planning. This algorithm is based on fitness sharing genetic algorithm, clustering and evolution of multiple populations, which can keep the diversity of the solution path, and decrease the operating time because of the independent evolution of each subpopulation. The multi-path planning algorithm is demonstrated by a number of two-dimensional path planning problems. The results show that the multi-path planning algorithm has the following characteristics: high searching capability, rapid convergence and high reliability.     

Broaching prediction in the light of an enhanced mathematical model,with higher-order terms taken into account

 We have attempted to develop a more consistent mathematical model for capsizing associated with surf-riding in following and quartering waves by taking most of the second-order terms of the waves into account. The wave effects on the hull maneuvring coefficients were estimated, together with the hydrodynamic lift due to wave fluid velocity, and the change in added mass due to relative wave elevations. The wave effects on the hydrodynamic derivatives with respect to rudder angles were estimated by using the Mathematical Modelling Group (MMG) model. Then captive ship model experiments were conducted, and these showed reasonably good agreements between the experiments and the calculations for the wave effects on the hull and the rudder maneuvring forces. It was also found that the wave effects on restoring moments are much smaller than the Froude–Krylov prediction, and the minimum restoring arm appears on a wave downslope but not on a wave crest amidship. Thus, an experimental formula of the lift force due to the heel angle of the ship is provided for numerical modelling. Numerical simulations were then carried out with these second-order terms of waves, and the results were compared with the results of free-running model experiments. An improved prediction accuracy for ship motions in following and quartering seas was demonstrated. Although the boundaries of the ship motion modes were also obtained with both the original model and the present one, the second-order terms for waves are not so crucial for predicting the capsizing boundaries themselves. Received: June 20, 2002 / Accepted: October 10, 2002 Acknowledgments. This research was supported by a Grant-in-Aid for Scientific Research of the Ministry of Education, Culture, Sports, Science and Technology of Japan (No. 13555270). The authors thank Prof. N. Rakhmanin of the Krylov Ship Research Institute for providing the Russian literature, as well as Mr. H. Murata of NHK (Japan Broadcasting Corporation) for translating it into Japanese. Address correspondence to: N. Umeda (e-mail: umeda@naoe.eng.osaka-u.ac.jp)     

Modeling of Double Lane Change Maneuver of Vehicles

Lane change maneuver is one of most riskiest driving tasks. In order to increase the safety level of the vehicles during this maneuver, design of lane change assist systems which are based on dynamics behavior of driver-vehicle unit is necessary. Therefore, modeling of the maneuver is the first step to design the driver assistance system. In this paper, a novel method for modeling of lateral motion of vehicles in the standard double-lane-change (DLC) maneuver is proposed. A neuro-fuzzy model is suggested consisting of both the vehicle orientation and its lateral position. The inputs of the model are the current orientation, lateral position and steering wheel angle, while the predicted lateral position and orientation of the vehicle are the outputs. The efficiency of the proposed method is verified using both simulation results and experimental tests. The simulation and experimental maneuvers are performed in different velocities. It is shown that the proposed method can effectively reduce the undesirable effects of environmental disturbances and is significantly more accurate in comparisons with the results in the recent available papers. This method can be used to personalize the advanced driver assistance systems.